Lens recommendations required for trip to Everest Base Camp

I will be taking a trip to the Everest Base Camp in the middle of this year and I would like to add 2 additional lenses to take with me. This what I have so far as photo gear (not all lenses will be taken):

Nikon D800 (taking)

Nikon 85mm 1.4G (taking)

Nikon 35-70mm 2.8D zoom

Nikon 105mm 1.8 AIS

Nikon 50mm 1.4 AIS

Nikon 180mm 2.8 ED AIS (purchasing soon, taking)

I would like to add a wide angle lens, prime or zoom centered around 20mm. I would also like to add a 400mm prime, older manual focus lens.

The wide lens will be used to take landscape images of the mountains and the 400mm will be used for astro-photography as that region of the world has some of the clearest/darkest skies, plus I will be at high altitudes.

I would like to purchase used older lenses as my budget for these two lenses would be around $1000. My main concern is image quality such as corner to corner sharpness, contrast, colors, distortion, etc. Since these are for still images, slow lenses will be perfect. I plan on taking a small portable tripod and can add a motorized star tracker for longer exposures for deep sky photos. I would love to take a Catadioptric telescope but can't because of the weight. Please let me know your thoughts and recommendations.